T型三电平逆变器中点电位平衡电路及控制

A T-type Three-level Inverter Neutral-point Potential Balancing Circuit and Control

直流母线电压中点电位不平衡是T型三电平逆变器的拓扑结构造成的固有问题。这里从T型三电平逆变器的拓扑结构出发,分析了空间矢量脉宽调制(SVPWM)中大、中和小矢量对中点电位不平衡的影响,针对中点电位不平衡,在电源侧并联一个半桥模块且中点与母线中点串联电感的平衡电路,然后对平衡电路被控对象进行建模与分析,推导出中点电压平衡控制框图,通过对上、下电容进行充放电控制,控制中点电位达到平衡,最后,搭建了T型三电平逆变器实验平台,进行了仿真和实验验证,实验结果验证了所提平衡电路和控制的有效性和可行性。

The neutral-point potential imbalance of the direct current bus voltage is an inherent problem of T-type three-level inverters caused by the topology.The influence of large,medium and small vectors in space vector pulse width modulation(SVPWM)on the midpoint potential unbalance is analysed from the topology of a T-type three-level inverter,for the neutral-point potential imbalance,a half-bridge module is connected in parallel on the power supply side and a balancing circuit with series inductors at the neutral-point and bus midpoint is connected in series,then the controlled object of the balancing circuit is modeled and analyzed,the neutral-point voltage balancing control block diagram is derived,the neutral-point potential is controlled to be balanced by charging and discharging the up-per and lower capacitors,finally,the experimental platform of T-type three-level inverter is built,the simulation and experimental verification are carried out,the experimental results verify the effectiveness and feasibility of the prop-osed balancing circuit and control.